(1) Field of the invention
The present invention generally relates to a cleaning unit provided in a xerographic image forming apparatus applicable to a facsimile machine, a printer, a copy machine and the like, and more particularly to a cleaning unit for removing residual dry developer (i.e. toner) from a photosensitive body in a xerographic machine and for storing the removed residual dry developer.
(2) Description of related art
FIG. 1 shows a xerographic image forming apparatus provided with a conventional cleaning unit. Referring to FIG. 1, a photosensitive belt 1 is wound around rollers 2. The rollers 2 are rotated in a clockwise direction, and thus the photosensitive belt 1 is moved at a predetermined speed in the clockwise direction as shown by an arrow. A discharger unit 3, a charger unit 4, a developing unit 5 having toner T (dry developer), a transfer unit 6 and a cleaning unit 7 are arranged so as to surround the photosensitive belt 1. A xerography process (an electrophotography process) is carried out on the photosensitive belt 1. The cleaning unit 9 has a cleaning blade 8 for removing residual toner from the photosensitive belt 1 and a housing 9 for storing the residual toner removed by the cleaning blade 8. A light beam 11, modulated in accordance with image data, is reflected by a mirror 10 and projected onto the photosensitive belt 1 to an exposure position set immediately after the charger unit 4. The light beam 11 scans the photosensitive belt 1, so that the photosensitive belt 1 is exposed.
The light beam 11 modulated in accordance with the image data scans the photosensitive belt 1 uniformly charged by the charger unit 4, and thus an electrostatic latent image corresponding to the image data is formed on the photosensitive belt 1. The electrostatic latent image is developed by the developer unit 5, so that an image is formed by the toner T on the photosensitive belt 1. The image formed by the toner T is transferred from the photosensitive belt 1 to a recording sheet 2 by the transfer unit 6, so that a toner image is formed on the recording sheet 2. After this, the toner image on the recording sheet 2 is fused and fixed thereon by a fixing unit (not shown).
After a process for transferring the image to the recording sheet 2, a small amount of toner which has not been transferred to the recording sheet 2 remains on the photosensitive belt 1. The residual toner is removed by the cleaning blade 8 from the photosensitive belt 1 along with other residual substances (silicon and other materials). The residual toner removed from the photosensitive belt 1 is stored in the housing 9.
In the conventional cleaning unit 7 described above, an end of the cleaning blade 8 is in contact with the surface of the photosensitive belt 1 as shown in FIG. 2. The cleaning blade 8 is inclined in a direction of the pull of gravity (G) so that the residual toner removed from the photosensitive belt 1 is moved by its own weight along the cleaning blade 8. While the photosensitive belt 1 is being moved, the residual toner T' is scraped from the surface of the photosensitive belt 1 by the cleaning blade 8. The scraped toner T' is accumulated on a region facing on the end of the cleaning blade 8. The scraped toner T' reaching the surface of the cleaning blade 8 continuously moves along the surface of the cleaning blade 8 in a direction indicated by an arrow A. The scraped toner T' that has slidden on the cleaning blade 8 is stored in the housing 9. The toner stored in the housing 9 is fed to the developing unit 5 by a toner recovery system (not shown).
In the conventional cleaning unit, there is no mechanism for leading the scraped toner T' accumulated on the region in front of the cleaning blade 8 to the surface of the cleaning blade 8. Thus, a large amount of toner is accumulated on the region in front of the cleaning blade 8. As a result, it is hard to efficiently feed the scraped toner T' into the housing 9.